1. Technical Field
The present disclosure relates to a semiconductor package structure and a manufacturing method thereof. More particularly, the present disclosure relates to a light emitting diode (LED) package structure and a manufacturing method thereof.
2. Description of Related Art
LEDs generally offer a number of advantageous characteristics such as long product life, compact size, high shock resistance, low heat generation and low power consumption, etc. As a result LEDs are widely employed in household applications and as the light source or indicator of a variety of equipment. Recent developments of new LEDs are in the areas of multiple colors and high brightness. Accordingly, LEDs are further employed in applications such as large outdoor bulletin boards, traffic signals and related fields. In the future, LEDs may even become the primary light source for illumination that not only conserve electricity but also are environmentally friendly.
Among the white-light LED package structures commonly adopted in the market, a type of white-light LED is composed of a blue-light LED chip and yellow phosphor. A prior art manufacturing method of a white-light LED package structure typically disposes a blue-light LED chip on a base and wire bonds the blue-light LED chip with the base. Afterwards, using spin coating, dispensing, spray coating, molding or any other suitable process on the base, a yellow fluorescent layer is formed on the blue-light LED chip. A portion of the yellow fluorescent layer emits yellow light upon excitation by the blue light emitted by the blue-light LED chip, and in turn the yellow light, combined with the blue light emitted by the blue-light LED chip, produces white light. However, a yellow fluorescent layer formed by spin coating, dispensing, spray coating or the like tends to suffer from excessive usage of phosphor powder and results in uneven thickness of the layer. That is, when the blue light emitted by the blue-light LED chip traverses through a yellow fluorescent layer of a greater thickness, the white-light LED package structure may produce a yellowish halo, causing the color of the light emitted by the LED package structure to be uneven overall.
In order to address the problem associated with uneven spin-coating of the fluorescent layer, U.S. Pat. No. 6,395,564 and U.S. Patent Publication No. 2009/0261358 disclose a technique that involves spraying the fluorescent layer directly on wafers and forming white-light LED package structures after cutting the wafers. However, such prior art technique suffers from the problem of lowered scattering efficiency during the process of the yellow fluorescent layer emitting yellow light upon excitation by the blue light. Additionally, as difference in wavelengths may result from crystalline growth on wafers, manufacturing costs tend to increase if the difference in wavelengths is to be rectified by way of spin-coating fluorescent layer on wafers.
In order to address the problem associated with low scattering efficiency, U.S. Pat. No. 6,630,691 discloses a manufacturing method of a phosphor layer. Ceramic glass and phosphor are combined under high temperature to result in a eutectic process that forms a fluorescent substrate, which is pasted to LED chips to avoid the issue of low scattering efficiency and enhance the uniformity of light generated by the LED package structure. However, as such prior art technique provides no electrode design for the fluorescent substrate, the use of this technique is limited to flip chip LED chips.